Arginine supplements can enhance Haematococcus pluvialis astaxanthin production, study finds

13 Dec 2023 --- A significant advancement has been made in studying astaxanthin production by researchers from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences. They demonstrated that arginine supplements can enhance the growth and production of the chemical carotenoid taken from Haematococcus pluvialis, the green algae from which it is naturally produced.

Boosting astaxanthin production is a primary concern of researchers worldwide. Researchers have actively explored various methods to enhance astaxanthin production in Haematococcus pluvialis and extract it in its whole form. The current research showed that arginine can contribute to the growth, astaxanthin and lipid production and stress responses in Haematococcus pluvialis, under high light conditions. 

“We have been looking for an economic, faster and healthier way for astaxanthin production in Haematococcus pluvialis, and this is what we found,” says Dr. Qing Huang, assistant professor at the School of Agricultural Economics and Rural Development, Renmin University of China.

The researchers compared different additives that can promote algal growth and astaxanthin accumulation in Haematococcus pluvialis. Arginine was identified as the most efficient and economical.

Growing algal compounds
In this research, scientists compared different substances that can help the Haematococcus pluvialis algae grow and produce the astaxanthin compound. The research findings were published in Biosource Technology.

During the second stage of cultivation, known as the red stage, microalgae are subjected to abiotic stress, such as high light, which can reduce photosynthesis efficiency due to the overproduction of reactive oxygen species (ROS), which leads to a decrease in overall cell growth, astaxanthin and lipid production. 

The researchers resolved the complication by supplementing the growth medium with amino acids to reduce ROS explosion and improve microalgae’s biomass and astaxanthin productivity. Chinese researchers posit that arginine enhances the astaxanthin production of its natural producer, Haematococcus pluvialis (Credit: Algicel).  

Arginine works by activating specific pathways in the algae, controlling certain genes related to carotenoids and lipids. It improves how the algae uses carbon and increases the expression of several genes involved in lipid and astaxanthin production. The combination of effects produces better algal growth, higher astaxanthin levels and increased lipid production.

The economical way of farming Haematococcus pluvialis is to simultaneously achieve biomass, astaxanthin and lipids using less expensive chemicals. The application of arginine exerts a synergic effect on biomass, astaxanthin and lipids by improving carbon use, activating the arginine pathway and regulating carotenoid and lipid-related genes. 

Genes related to arginine catabolism were up-regulated at the cultivation and astaxanthin induction stages, signifying their importance in astaxanthin synthesis and growth.

Boosting astaxanthin
Astaxanthin, a potent keto carotenoid, has powerful antioxidant properties. The study results provide a significant mechanism and applicability of using exogenous arginine and high light to stimulate Haematococcus pluvialis bioproducts such as astaxanthin.

The antioxidants scavenge free radicals and shield cells against oxidative damage. By enhancing the antioxidant defense mechanism, arginine indirectly supports astaxanthin production by reducing oxidative stress and promoting cell survival.

Transcriptome analysis revealed that arginine up-regulated transcription levels of genes involved carbon fixing, lipid biosynthesis, pyruvate metabolism, carotenoid, tricarboxylic acid cycle and arginine and proline metabolism. 

Meanwhile, Iceland-based astaxanthin producer Algalif and vitamins manufacturer and supplier Divi’s Nutraceuticals partnered to launch high-concentration astaxanthin beadlets, AstaBeads. The product taps into the growing trend of natural, sustainable ingredients for sports nutrition and healthy aging products, while the beadlet format delivers high bioavailability.

By Inga de Jong